The present invention relates to an armature for a rotating electrical machine including a cylindrical core having a plurality of longitudinally extending slots that are dispersedly arranged in a circumferential direction, and coils wound around the slots, and to a manufacturing method thereof.
Generally, a rotating electrical machine used as a motor (electric motor) or a generator (electrical generator) or the like is required to be capable of providing greater output while being smaller in size. Accordingly, one of the important problems to be solved is to increase the energy efficiency of the rotating electrical machine. As the techniques for increasing the energy efficiency of the rotating electrical machine, for example, the technique for improving the space factor of the coils in the armature of the rotating electrical machine has conventionally been known.
One reference that describes an improvement in the space factor of the coils may be Japanese Patent Application Publication JP-A-2008-167567 listed below. Japanese Patent Application Publication JP-A-2008-167567 describes a stator as an armature for a rotating electrical machine, in which the coils are each formed using a rectangular wire conductor having a substantially rectangular cross-sectional shape, whereby the space factor is improved and the ampere-turn per unit cross-sectional area is increased. Thus, the output of the rotating electrical machine is improved.
In the rotating electrical machine described in Japanese Patent Application Publication JP-A-2008-167567, each of the slots of the stator is an open slot (a slot in which an opening that is open radially inward is equal to or greater in the circumferential width than the portion for accommodating the coils), and the coils preformed into a prescribed shape through continuous winding are radially inserted from the openings of the slots while being deformed circumferentially and longitudinally, and thereby being wound around the slots. Thus, the number of portions to be electrically connected after the insertion of the coils into the slots can be reduced, whereby the productivity can be improved.
Another reference that describes an improvement in the space factor of the coils may be Japanese Patent No. 3798968 listed below. Japanese Patent No. 3798968 describes a stator as an armature for a rotating electrical machine, in which fine wires are stacked circumferentially and radially to form each coil of a prescribed shape. Here, in order to improve the space factor in each slot, the fine wires are stacked and bundled so as to have a cross-sectional shape that conforms to that of the slot.
In the stator of the rotating electrical machine described in Japanese Patent No. 3798968, each of the slots of the core of the stator is a semi-open slot (a slot in which an opening that is open radially inward is smaller in the circumferential width than the portion for accommodating the coils). Thus, also by increasing the effective magnetic flux effecting between the stator and the rotor as a field, the output of the rotating electrical machine is improved. Here, in accordance with the use of the semi-open slot type core in the stator of the rotating electrical machine, the fine wires are preformed so as to be curved radially inward and to be longitudinally stacked at coil end portions located on one longitudinal side of the coils. In other words, at the site where the fine wires forming each coil extend radially, the fine wires are not circumferentially stacked. Thus, the circumferential width of that portion is made smaller than the width of the opening on the radially inner side of each slot. Then, the preformed coils are longitudinally inserted from the curved coil end portion side to be wound around the slots of the core.